1. Field of the Invention
The present invention is directed to a technique for detecting the position of a movable part which is disposed movably within processing space inside a chamber.
2. Description of the Related Art
During the processing of an object-to-be-processed which is a substrate for instance, for the purpose of controlling of ambient atmosphere or preventing a chemical solution from splattering, the object-to-be-processed and an apparatus for executing the processing may occasionally disposed within the same processing space inside a chamber. For such processing, the structure elements which form the apparatus must be located at appropriate positions.
When there is a movable member which is so structured to move within processing space, it is necessary to confirm whether the movable member is located at an appropriate position. For this purpose, position detection is executed which utilizes image processing which is subsequent to imaging of members which are located within the processing space, and whether the positions of the members are appropriate is then determined. However, the position of an imaging device itself such as a camera for imaging could be a deviated position. Several techniques to deal with such situations have been proposed (Patent Documents 1 through 6 for instance).
Patent Document 1: JP10-135100A
Patent Document 2: JP11-005056A
Patent Document 3: JP11-131231A
Patent Document 4: JP2006-268032A
Patent Document 5: JP2006-284890A
Patent Document 6: JP2002-135644A
According to the techniques described in Patent Documents 1 through 3 among the patent documents above, a captured image is analyzed and deviation of a camera if any detected suspends processing. This is to avoid failure which can be otherwise caused by continuance of the processing in an abnormal condition. Meanwhile, the techniques described in Patent Documents 4 and 5 require installment of a mover mechanism which is for changing the posture of a camera. In response to detection of deviation of the camera, the mover mechanism moves the camera in an attempt to eliminate the deviation. While the technique according to Patent Document 6 is directed to detection of deviation of a camera, this patent document does not describe post-detection processing in detail.
In the event that a movable part is disposed inside a chamber for the purpose of executing some processing, it is reasonable to suspend the processing owing to deviation of the movable part. In contrast, suspension of processing owing to deviation of a camera (imaging device) should be avoided as much as possible in terms of the processing throughput. However, Patent Documents 1 through 3 and 6 are silent about a method which allows continuation of the processing even despite detected deviation of the imaging device. On the other hand, when the imaging device itself is equipped with the function of correcting deviation as described in Patent Documents 4 and 5, the structure of the apparatus becomes too complex and the processing cost grows.
Against this background, there is a need toward a technique for appropriately detecting the position of a movable part even despite deviation of an imaging device without spending a large cost. The conventional techniques described above however do not satisfy the need.